24 hours is too short for you.
I'd recommend you to go shopping instead. Beautiful islands of the Philippines are outside Manila. Manila is too dense. You can visit the following Malls and nearby cities.
From the NAIA (Ninoy Aquino International Airport) proceed to
MALL OF ASIA - it is so far biggest mall in asia in terms of area and variety of choices. You can spend your whole day there, but don't! Try to budget your time.
Proceed to Makati and Ayala Avenue..
Greebelt 1, 2, 3, 4 are the places to hang-out at night, open restobars and these are the places where expats hang-out. Everything is walkable, but be careful with your valuable things.
From SM Makati, pass by the sky walk to cross Landmark then to Greenbelt, then proceed to ROCKWELL POWER PLANT, then Market Market. If you still have time, visit SM Megamall (you'll see how different the malls there from here in UAE). Their department store is by floor level aside from the branded shopping outlets inside the mall..
First floor - hypermarket, second floor - all cosmetics, 3rd floor - ladies, maternity and babies, 4th floor - men fashions and so on..). They have food court in ground floor and in upper level and they have huge parking spaces too.
Manila, Makati and its neighboring cities are full of shopping haven.
Outside these cities, you can see their beautiful islands. Since you only have 24 hours, better Enjoy shopping in Philippines.